Cathode active material precursor, cathode active material, lithium secondary battery and method of manufacturing the same

ABSTRACT

A cathode active material precursor according to embodiments of the present invention includes a composite hydroxide particle in which primary precursor particles are aggregated. The primary precursor particles include a particle having a triangular shape in which a minimum interior angle is 300 or more and a ratio of a length of a short side relative to a length of a long side is 0.5 or more. A cathode active material and a lithium secondary having improved high temperature stability is provided using the cathode active material precursor.

CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY

This application claims priority to Korean Patent Application No.10-2020-0103395 filed on Aug. 18, 2020 in the Korean IntellectualProperty Office (KIPO), the entire disclosure of which is incorporatedby reference herein.

BACKGROUND 1. Field

The present invention relates to a cathode active material precursor, acathode active material, a lithium secondary battery and methods ofmanufacturing the same. More particularly, the present invention relatesto a cathode active material precursor including a plurality of metalelements, a cathode active material, a lithium secondary battery andmethods of manufacturing the same.

2. Description of the Related Art

A secondary battery which can be charged and discharged repeatedly hasbeen widely employed as a power source of a mobile electronic devicesuch as a camcorder, a mobile phone, a laptop computer, etc., accordingto developments of information and display technologies. The secondarybattery includes, e.g., a lithium secondary battery, a nickel-cadmiumbattery, a nickel-hydrogen battery, etc. The lithium secondary batteryis highlighted due to high operational voltage and energy density perunit weight, a high charging rate, a compact dimension, etc.

For example, the lithium secondary battery may include an electrodeassembly including a cathode, an anode and a separation layer(separator), and an electrolyte immersing the electrode assembly. Thelithium secondary battery may further include an outer case having,e.g., a pouch shape.

A lithium metal oxide may be used as an active material for a cathode ofthe lithium secondary battery. For example, the lithium metal oxide mayinclude a nickel-based lithium metal oxide. A nickel-containingprecursor compound may be used to prepare the nickel-based lithium metaloxide.

Recently, as an application range of the lithium secondary battery hasbeen expanded from a small electronic device to a large scaled devicesuch as a hybrid vehicle, a content of nickel is increasing to achievesufficient capacity and power. However, as the content of nickelincreases, reliability of the cathode active material may bedeteriorated due to mismatch and side reaction with lithium.

For example, Korean Registered Patent Publication No. 10-0821523discloses a method for manufacturing a cathode active material using alithium composite metal oxide, but still possess the problem of a highnickel-based cathode active material.

SUMMARY

According to an aspect of the present invention, there is provided acathode active material precursor having improved stability.

According to an aspect of the present invention, there is provided acathode active material having improved stability.

According to an aspect of the present invention, there is provided alithium secondary battery having improved stability.

According to an aspect of the present invention, there is provided amethod of manufacturing a cathode active material precursor havingimproved stability.

According to an aspect of the present invention, there is provided amethod of manufacturing a cathode active material for a lithiumsecondary battery having improved stability.

According to exemplary embodiments of the present invention, a cathodeactive material precursor includes a composite hydroxide particle inwhich primary precursor particles are aggregated. The primary precursorparticles include a particle having a triangular shape in which aminimum interior angle is 300 or more and a ratio of a length of a shortside relative to a length of a long side is 0.5 or more.

In some embodiments, the composite hydroxide particle may contain anexcess of nickel among metals included therein and has a specificsurface area of 1.5 m²/g or less.

In some embodiments, the composite hydroxide particle may have aspecific surface area of 1 m²/g or less.

In some embodiments, a molar ratio of nickel in the metals included inthe composite hydroxide particle may be 0.8 or more.

In some embodiments, the composite hydroxide particle may furtherinclude cobalt.

In some embodiments, the composite hydroxide particle may furtherinclude manganese.

In some embodiments, the composite hydroxide particle may be representedby Chemical Formula 1:

Ni_(α)Co_(β)M_(γ)(OH)_(z)  [Chemical Formula 1]

In Chemical Formula 1, M includes at least one selected from the groupconsisting of Mg, Sr, Ba, B, Al, Si, Mn, Ti, Zr and W, 0.8≤α≤0.95,0≤γ/(α+β)≤0.13, 0≤γ≤0.11 and 1.9≤z≤2.1.

In some embodiments, the ratio of the length of the short side relativeto the length of the long side may be 0.8 or more.

According to exemplary embodiments of the present invention, a cathodeactive material for a secondary battery includes a lithium compositeoxide particle formed from the cathode active material precursor asdescribed above.

In some embodiments, the lithium composite oxide particle may have anamorphous shape.

According to exemplary embodiments of the present invention, a lithiumsecondary battery includes a cathode including the cathode activematerial as described above, and an anode facing the cathode.

In a method of manufacturing a cathode active material precursor, areaction solution containing a metal source is prepared. Aco-precipitate is formed through a co-precipitation reaction in thereaction solution. A solid content in the reaction solution is 50 wt %or more after the co-precipitation reaction. A composite hydroxideparticle is formed in which primary precursor particles are aggregatedby the co-precipitation reaction, and the primary precursor particlesinclude a particle having a triangular shape in which a minimum interiorangle is 30° or more and a ratio of a length of a short side relative toa length of a long side is 0.5 or more.

In some embodiments, the co-precipitation reaction may be performedunder a condition in which a pH value is changed from 11.8 or more to10.8 or less. In some embodiments, the co-precipitation reaction isperformed for 120 hours or more.

In a method of manufacturing a cathode active material for a secondarybattery, the cathode active material precursor as described above isprepared. A preliminary lithium composite oxide particle is formed byreacting the cathode active material precursor with a lithium source.The preliminary lithium composite oxide particle is post-treated.

In some embodiments, the preliminary lithium composite oxide particlemay have a specific surface area of 0.12 m²/g or less.

In some embodiments, the post-treating may include at least one ofcoating, heat-treating, washing and drying.

In some embodiments, in the formation of the preliminary lithiumcomposite oxide particle, firing may be performed after reacting thecathode active material precursor with the lithium source.

According to exemplary embodiments, a cathode active material precursormay include a composite hydroxide particle formed by an aggregation ofprimary precursor particles including a particle having a specifictriangular shape.

For example, a specific surface area of the primary precursor particlesmay be decreased and a contact area between the primary precursorparticles may be increased due to the specific triangular shape thereof.Accordingly, the specific surface area of the cathode active materialformed from the composite hydroxide particles may be reduced, structuralstability may be improved, and high temperature life-span and storageproperties may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating a lithiumsecondary battery in accordance with exemplary embodiments exemplaryembodiments.

FIG. 2 is an SEM image of a precursor particle (a composite hydroxideparticle) for a cathode active material according to exemplaryembodiments.

FIG. 3 is an SEM image of composite hydroxide particles used inComparative Examples 1 to 3.

FIG. 4 is an SEM image of composite hydroxide particles used inComparative Examples 4 to 6.

FIG. 5 is an SEM image of a preliminary lithium composite oxide particleformed from composite hydroxide particles of Example 1.

FIGS. 6 and 7 are SEM images of preliminary lithium composite oxideparticles formed from composite hydroxide particles of ComparativeExamples 1 and 4, respectively.

FIGS. 8 and 9 are SEM images of cathode active materials for a secondarybatteries of Example 7 and Comparative Example 3, respectively.

FIG. 10 is a schematic diagram illustrating a length ratio of a longside relative to a short side of a primary precursor particle.

DETAILED DESCRIPTION OF THE EMBODIMENTS

According to exemplary embodiments of the present invention, there isprovided a cathode active material precursor including a compositehydroxide particle formed from an assembly of primary precursorparticles having a specific shape, a cathode active material formed fromthe same, and a lithium secondary battery including the cathode activematerial.

Hereinafter, the present invention will be described in detail withreference to the accompanying drawings. However, those skilled in theart will appreciate that such embodiments described with reference tothe accompanying drawings are provided to further understand the spiritof the present invention and do not limit subject matters to beprotected as disclosed in the detailed description and appended claims.

The cathode active material precursor may include a composite hydroxideparticles in the form of a secondary particle in which a plurality ofprimary precursor particles are aggregated or assembled.

The primary precursor particle may include a particle having atriangular shape in which the smallest interior angle is 300 or more anda ratio (that may be referred to as an aspect ratio) of a length of ashort side relative to a length of a long side is 0.5 or more. The longside may mean the longest side among three sides of a triangle, and theshort side may mean the shortest side among three sides of a triangle.

In some embodiments, at least one or at least two of the inner angles ofthe primary precursor particle may be from 300 to 600. In someembodiments, the smallest interior angle of the primary precursorparticle may be from 30° to 60°.

The composite hydroxide particle formed from the primary precursorparticle that may include a particle having the triangular shape mayhave enhanced high-temperature stability when being converted into alithium composite oxide by firing. Further, high-temperature life-spanand storage properties of a lithium secondary battery using the lithiumcomposite oxide as a cathode active material may be improved.

A maximum value of the aspect ratio may be 1. If the aspect ratio isless than 0.5, a specific surface area of the composite hydroxideparticle formed by aggregation of the primary precursor particles mayexcessively increase, and a contact area between the primary precursorparticles may be reduced. In this case, the high-temperature stabilityof the cathode active material formed from the composite hydroxideparticles may be degraded.

In a preferable embodiment, the aspect ratio in the triangular shape maybe 0.8 or more.

For example, the triangular shape may be a shape of one surface of theprimary precursor particle. For example, the shape of the primaryprecursor particle may include a triangular plate, a triangular prism, atriangular cylinder, a tetrahedron, or the like.

For example, the term “the triangular shape” used herein may include ashape in which two of three sides are in contact with each other to forma vertex, and may also include two virtual extended sides extendingwithin about 20% of each side are in contact with each other to form avirtual vertex.

For example, one surface of the primary precursor particles may have atriangular shape to have a large surface area, and may contact atriangular-shaped surface of another primary precursor particle. In thiscase, an interfacial area at which the particles are in contact witheach other in a stack or overlap of the primary precursor particles maybe increased. Thus, structural stability of the composite hydroxideparticle formed as the secondary particle may be improved.

For example, the composite hydroxide particle may be a substance of acation component and a counter ion component. The cation component mayinclude, e.g., a metal ion. The counter ion component may include ahydroxide ion (OH⁻), or the like. For example, the composite hydroxideparticle may be a composite hydroxide including two or more metalelements.

In some embodiments, the composite hydroxide particle may include anexcess amount of nickel among metals.

The term “excess amount” used herein may indicate the largest molefraction or molar ratio among a plurality of components. Specifically,the term “excess amount” may indicate more than 50 mol % based on totalmoles of metals included in the composite hydroxide particle.

In some embodiments, the composite hydroxide particle may furtherinclude cobalt and/or manganese. For example, the composite hydroxideparticle may include a nickel-cobalt-based precursor, anickel-manganese-based precursor or a nickel-cobalt-manganese(NCM)-based precursor.

In exemplary embodiments, the composite hydroxide particle may berepresented by Chemical Formula 1 below.

Ni_(α)Co_(β)M_(γ)(OH)_(z)  [Chemical Formula 1]

In Chemical Formula 1, 0.8≤α≤0.95, 0≤γ/(α+β)≤0.13, 0≤δ≤0.11, and1.9≤z≤2.1. M may represent a dopant or a transition metal. M mayinclude, e.g., at least one of Mg, Sr, Ba, B, Al, Si, Mn, Ti, Zr and W.

In an embodiment, a content or a molar ratio of Co may be greater thanthat of M. Accordingly, a resistance of the cathode electrode activematerial may be decreased to increase conductivity. M as a dopant mayfurther improve long-term stability and high-temperature stability ofthe cathode active material.

In exemplary embodiments, a specific surface area of the compositehydroxide particle may be 1.5 m²/g or less. If the specific surface areais more than 1.5 m²/g, a specific surface area of the lithium compositeoxide particle prepared from the composite hydroxide particle may beexcessively increased. In this case, a surface structure of the cathodeactive material may become unstable under a high temperature condition.Preferably, the specific surface area of the composite hydroxideparticle may be 1 m²/g or less. In an embodiment, the specific surfacearea of the composite hydroxide particle may be 0.2 m²/g or more or 0.4m²/g or more.

The composite hydroxide particle may be prepared through aco-precipitation reaction of metal salts (metal sources). The metalsalts may include a nickel salt, a cobalt salt and/or a manganese salt.

Examples of the nickel salt include nickel sulfate, nickel hydroxide,nickel nitrate, nickel acetate, and hydrates thereof. Examples of thecobalt salt include cobalt sulfate, cobalt nitrate, cobalt carbonate,and hydrates thereof. Examples of the manganese salt include manganesesulfate, manganese acetate, and hydrates thereof.

The metal salts may be mixed with a precipitating agent and/or achelating agent at a ratio satisfying the content or concentration ratioof each metal described with reference to Chemical Formula 1 to form anaqueous solution. The aqueous solution may be co-precipitated in areactor to prepare the composite hydroxide particle.

The precipitating agent may include an alkaline compound such as sodiumhydroxide (NaOH), sodium carbonate (Na₂CO₃), or the like. The chelatingagent may include, e.g., aqueous ammonia (e.g., NH₃H₂O), ammoniumcarbonate (e.g., NH₃HCO₃), or the like.

In exemplary embodiments, a reaction solution in which theco-precipitation reaction occurs may include a metal source and aco-precipitate. During the co-precipitation reaction, a solid content inthe reaction solution may be maintained as about 50 weight percent (wt%) or more. For example, a total weight ratio of the co-precipitate maybe about 50 wt % or more of the reaction solution. If the solid contentin the reaction solution is less than 50 wt %, a conventionalneedle-shaped precursor may be formed. In exemplary embodiments, if thesolid content in the reaction solution is 50 wt % or more, the primaryprecursor particle having the triangular shape may be more easilyformed.

A temperature of the co-precipitation reaction may be controlled in,e.g., a range from about 40° C. to 60° C. A reaction time may be atleast about 120 hours.

If the co-precipitation reaction time is 120 hours or more, the solidcontent in the reaction solution after completion of theco-precipitation reaction may be 50 wt % or more. In this case, theprimary precursor particles having the triangular shape may beeffectively formed.

In exemplary embodiments, the co-precipitation reaction may be performedunder a condition in which pH may be changed from 11.8 or more to 10.8or less. The triangular-shaped primary precursor particles may beeffectively formed under the pH change condition.

In some embodiments, the co-precipitation reaction may be performed atan oxygen concentration of 0.1% or less. If the oxygen concentration isbeyond the above range, a shape of the resulting composite hydroxideparticle may become a needle-like shape and a specific surface areathereof may increase.

In exemplary embodiments, the primary precursor particle may be dried atabout 80° C. to 160° C. In this case, a plurality of the primaryprecursor particles may be aggregated to form the composite hydroxideparticle in the form of the secondary particle. The primary precursorparticles may be washed with an alkaline aqueous solution and/or waterbefore being dried.

In example embodiments, the lithium composite oxide particle (thecathode active material) may be prepared by mixing and reacting thecomposite hydroxide particle and a lithium source. The lithium sourcemay include, e.g., a lithium salt such as lithium carbonate, lithiumnitrate, lithium acetate, lithium oxide, lithium hydroxide, etc. Thesemay be used alone or in a combination thereof.

In exemplary embodiments, the reaction between the composite hydroxideparticle and the lithium source may include a heat treatment (a firstfiring). For example, in an embodiment, a temperature of the heattreatment may be in a range from about 600° C. to 1000° C.

In exemplary embodiments, a specific surface area of a preliminarylithium composite oxide particle formed by the first firing may be 0.12m²/g or less. When the cathode active material is formed through thepreliminary lithium composite oxide particles having the specificsurface area of 0.12 m²/g or less, high temperature stability may befurther improved.

In some embodiments, the specific surface area of the preliminarylithium composite oxide particles may be 0.06 m²/or more. When thespecific surface area is less than 0.06 m²/g, movement and transport oflithium ions may be restricted and power and capacity of the secondarybattery may be degraded.

The preliminary lithium composite oxide particle may be subjected to apost-treatment process such as a coating, an additional heat treatment(a second firing), a washing and a drying to form the cathode activematerial.

For example, lithium impurities or unreacted water-soluble impuritiesmay be removed by the washing, and the additional heat treatment (thesecond firing) process may fix metal elements and increasecrystallinity. In some embodiments, the second firing may be performedduring the coating.

The lithium composite oxide particle may include an oxide includinglithium and other elements such as a transition metal.

The lithium composite oxide particle may include nickel. Nickel may beincluded in an excess amount relatively to other elements except forlithium and oxygen of the lithium composite oxide particle.

Nickel may serve as a metal associated with the capacity of the lithiumsecondary battery. In exemplary embodiments, nickel may be included inthe excess amount relatively to other elements except for lithium andoxygen of the lithium composite oxide particle to remarkably improve thecapacity of the secondary battery.

In exemplary embodiments, a molar ratio of nickel among elements otherthan lithium and oxygen of the lithium composite oxide particle may be0.8 or more.

In some embodiments, the lithium composite oxide particle may be anickel-cobalt-based lithium composite oxide further containing cobalt.In some embodiments, the lithium composite oxide particle may be anickel-cobalt-manganese (NCM)-based lithium composite oxide furtherincluding cobalt and manganese.

In exemplary embodiments, the lithium composite oxide particle may berepresented by Chemical Formula 2 below.

Li_(x)Ni_(a)Co_(b)M_(c)O_(y)  [Chemical Formula 2]

In Chemical Formula 2, M is at least one of Al, Zr, Ti, B. Mg, Mn, Ba,Si, W, and Sr, 0.9≤x≤1.1, 1.9≤y≤2.1, 0.8≤a≤0.95, 0≤c/(a+b)≤0.13, and0≤c≤0.11.

For example, as a content of nickel increases, the capacity and power ofthe lithium secondary battery may be improved. However, if the contentof nickel is excessively increased, life-span, and mechanical andelectrical stability of the battery may be degraded. For example, if thecontent of nickel is excessively increased, defects such as ignition andshort circuit caused when a penetration by an external object occurs maynot be sufficiently suppressed. Accordingly, according to exemplaryembodiments, manganese (Mn) may also be distributed throughout theparticles to reduce or prevent chemical and mechanical instabilitycaused by nickel.

Manganese (Mn) may serve as a metal related to mechanical and electricalstability of a lithium secondary battery. For example, manganese maysuppress or reduce defects such as ignition and short circuit that mayoccur when the cathode is penetrated by the external object, and mayenhance the life-span of the lithium secondary battery. Cobalt (Co) maybe a metal related to conductivity or resistance of the lithiumsecondary battery.

If the molar ratio of Ni is less than 0.8, capacity and power may bereduced. If the molar ratio of Ni exceeds 0.95, the life-span ormechanical stability of the battery may be deteriorated.

In some embodiments, in Chemical Formula 2, 0.05≤b≤0.2, 0.03≤c≤0.11 and0.95<a+b+c≤11. In the above composition range, a balanced power,capacity, life-span and stability of the lithium composite oxideparticle may be achieved.

In exemplary embodiments, the lithium composite oxide particle may havea secondary particle structure formed by aggregation of primaryparticles.

An average particle diameter (D₅₀) of the primary particle in avolume-based cumulative distribution of a particle size may be in, e.g.,a range from about 0.5 μm to 1.2 μm. An average particle diameter (D₅₀)of the secondary particle in a volume-based cumulative distribution of aparticle size may be in, e.g., a range from about 9 μm to 12 μm. In theabove particle size range, cohesive and bonding force between theprimary particles may be improved, and high temperature stability mayalso be improved.

In a comparative example, a lithium composite oxide particles formedfrom a conventional needle-shaped precursor particle has an angularsurface shape of a quadrangle or more such as a crystal form of arectangular plate having an octahedron or hexahedron structure, arectangular column, a hexahedral or octahedral structure, etc.

In exemplary embodiments, the lithium composite oxide particle may havean amorphous shape substantially having no corner angle, and the lithiumcomposite oxide particle may not have a specific crystal shape and maynot have an angular shape of a polyhedron including a surface of aquadrangle, a pentagon or more.

FIG. 1 is a schematic cross-sectional view illustrating a lithiumsecondary battery in accordance with exemplary embodiments exemplaryembodiments.

Referring to FIG. 1, the lithium secondary battery may include a cathode130, an anode 140 and a separation layer 150 interposed between thecathode and the anode.

The cathode 130 may include a cathode current collector 110 and acathode active material layer 115 formed by coating a cathode activematerial on the cathode current collector 110.

A cathode slurry may be prepared by mixing and stirring the cathodeactive material in a solvent with a binder, a conductive agent and/or adispersive agent. The cathode slurry may be coated on the cathodecurrent collector 110, and then dried and pressed to form the cathode130.

The cathode current collector 110 may include stainless-steel, nickel,aluminum, titanium, copper or an alloy thereof. Preferably, aluminum oran alloy thereof may be used.

The binder may include an organic based binder such as a polyvinylidenefluoride-hexafluoropropylene copolymer (PVDF-co-HFP),polyvinylidenefluoride (PVDF), polyacrylonitrile,polymethylmethacrylate, etc., or an aqueous based binder such asstyrene-butadiene rubber (SBR) that may be used with a thickener such ascarboxymethyl cellulose (CMC).

For example, a PVDF-based binder may be used as a cathode binder. Inthis case, an amount of the binder for forming the cathode activematerial layer may be reduced, and an amount of the cathode activematerial may be relatively increased. Thus, capacity and power of thelithium secondary battery may be further improved.

The conductive agent may be added to facilitate electron mobilitybetween active material particles. For example, the conductive agent mayinclude a carbon-based material such as graphite, carbon black,graphene, carbon nanotube, etc., and/or a metal-based material such astin, tin oxide, titanium oxide, a perovskite material such as LaSrCoO₃or LaSrMnO₃, etc.

In exemplary embodiments, the anode 140 may include an anode currentcollector 120 and an anode active material layer 125 formed by coatingan anode active material on the anode current collector 120.

The anode active material may include a material commonly used in therelated art which may be capable of adsorbing and ejecting lithium ions.For example, a carbon-based material such as a crystalline carbon, anamorphous carbon, a carbon complex or a carbon fiber, a lithium alloy,silicon (Si)-based compound, tin, etc., may be used.

The amorphous carbon may include a hard carbon, cokes, a mesocarbonmicrobead (MCMB) fired at a temperature of 1,500° C. or less, amesophase pitch-based carbon fiber (MPCF), etc. The crystalline carbonmay include a graphite-based material such as natural graphite,graphitized cokes, graphitized MCMB, graphitized MPCF, etc. The lithiumalloy may further include aluminum, zinc, bismuth, cadmium, antimony,silicon, lead, tin, gallium, indium, etc.

The anode current collector 120 may include, e.g., gold, stainlesssteel, nickel, aluminum, titanium, copper or an alloy thereof,preferably may include copper or a copper alloy.

In some embodiments, a slurry may be prepared by mixing and stirring theanode active material with a binder, a conductive agent and/or adispersive agent in a solvent. The slurry may be coated on the anodecurrent collector 120, and then dried and pressed to form the anode 140.

The binder and the conductive agent substantially the same as or similarto those mentioned above may also be used in the anode. In someembodiments, the binder for forming the anode may include, e.g., anaqueous binder such as styrene-butadiene rubber (SBR) for compatibilitywith the carbon-based active material, and may be used together with athickener such as carboxymethyl cellulose (CMC).

The separation layer 150 may be interposed between the cathode 130 andthe anode 140. The separation layer 150 may include a porous polymerfilm prepared from, e.g., a polyolefin-based polymer such as an ethylenehomopolymer, a propylene homopolymer, an ethylene/butene copolymer, anethylene/hexene copolymer, an ethylene/methacrylate copolymer, or thelike. The separation layer 150 may also include a non-woven fabricformed from a glass fiber with a high melting point, a polyethyleneterephthalate fiber, or the like.

In some embodiments, an area and/or a volume of the anode 140 (e.g., acontact area with the separation layer 150) may be greater than that ofthe cathode 130. Thus, lithium ions generated from the cathode 130 maybe easily transferred to the anode 140 without a loss by, e.g.,precipitation or sedimentation. Thus, improvement of power and stabilitymay be efficiently realized through a combination with theabove-described composite hydroxide particle or the cathode activematerial.

In exemplary embodiments, an electrode cell may be defined by thecathode 130, the anode 140 and the separation layer 150, and a pluralityof the electrode cells may be stacked to form an electrode assembly thatmay have e.g., a jelly roll shape. For example, the electrode assemblymay be formed by winding, laminating or folding the separation layer150.

The electrode assembly may be accommodated together with an electrolytein an outer case 170 to define a lithium secondary battery. In exemplaryembodiments, a non-aqueous electrolyte may be used as the electrolyte.

For example, the non-aqueous electrolyte solution may include a lithiumsalt and an organic solvent. The lithium salt commonly used in theelectrolyte for the lithium secondary battery may be used, and may berepresented by Li⁺X⁻.

An anion of the lithium salt X⁻ may include, e.g., F⁻, Cl⁻, Br⁻, I⁻, NO₃⁻, N(CN)₂ ⁻, BF₄ ⁻, ClO₄ ⁻, PF₆ ⁻, (CF₃)₂PF₄ ⁻, (CF₃)₃PF₃ ⁻, (CF₃)₄PF₂⁻, (CF₃)₅PF⁻, (CF₃)₆P⁻, CF₃SO₃ ⁻, CF₃CF₂SO₃ ⁻, (CF₃SO₂)₂N⁻, (FSO₂)₂N⁻,CF₃CF₂(CF₃)₂CO⁻, (CF₃SO₂)₂CH⁻, (SF₅)₃C⁻, (CF₃SO₂)₃C⁻, CF₃(CF₂)₇SO₃ ⁻,CF₃CO₂ ⁻, CH₃CO₂ ⁻, SCN⁻, (CF₃CF₂SO₂)₂N⁻, etc.

The organic solvent may include. e.g., propylene carbonate (PC),ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate(DMC), ethylmethyl carbonate (EMC), methylpropyl carbonate, dipropylcarbonate, dimethyl sulfoxide, acetonitrile, dimethoxy ethane, diethoxyethane, vinylene carbonate, sulfolane, gamma-butyrolactone, propylenesulfite, tetrahydrofuran, etc. These may be used alone or in acombination thereof.

Electrode tabs may protrude from the cathode current collector 110 andthe anode electrode current collector 120 included in each electrodecell to one side of the outer case 170. The electrode tabs may be weldedtogether with the one side of the outer case 170 to form an electrodelead extending or exposed to an outside of the outer case 160.

The lithium secondary battery may be manufactured in, e.g., acylindrical shape using a can, a square shape, a pouch shape or a coinshape.

Hereinafter, preferred embodiments are proposed to more concretelydescribe the present invention. However, the following examples are onlygiven for illustrating the present invention and those skilled in therelated art will obviously understand that various alterations andmodifications are possible within the scope and spirit of the presentinvention. Such alterations and modifications are duly included in theappended claims.

Example 1

(1) Preparation of Composite Hydroxide Particle

5 m³ of water was put into a sealed co-precipitation reactor equippedwith a stirrer and a concentrator and having a volume of 5.5 m³, andthen nitrogen gas was bubbled for at least 4 hours to remove internaldissolved oxygen while maintaining an internal temperature at 63° C.15.1 kg of NaOH was added to the reactor, and 28% aqueous ammonia wasadded to the reactor to adjust a concentration of NH₃ to 24 g/L. A pH ofthe obtained reaction solution was 11.9.

While initially stirring the reaction solution at 175 rpm. NiSO₄.6H₂O,CoSO₄.H₂O and MnSO₄.H₂O were used to prepare a 2.0M metal mixed aqueoussolution with a molar ratio of Ni:Co:Mn=0.8:0.1:0.1. 2.2 M NaOH solutionas a pH control agent and 4.5 M ammonia solution as a chelating agentwere continuously added while bubbling N₂ to proceed with aco-precipitation reaction.

A residual liquid was continuously discharged to an outside of thereactor by the concentrator during the reaction, and the reactionproceeded for 157 hours while solid contents remained in the reactor.

The initial pH of 11.9 and the stirring rate of 175 rpm were graduallyreduced to 10.4 and of 141 rpm, respectively, until the reaction wascompleted to prevent a generation of new fine particles due to theincrease of the solid contents as the reaction proceeded.

The solids content in the final reactor was 69.6 wt %. A mother liquorafter the reaction completed was washed sequentially using 2.2M NaOHsolution and pure water, filtered and then dried at 120° C. for 12 hoursto obtain 6.5 tons of Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)₂ as a high-densitymetal composite hydroxide (a precursor A) which had an average particlesize (D₅₀) 12.1 μm, a tap density 2.17 g/cc, a BET 0.89 m²/g.

(2) Preparation of Preliminary Lithium Composite Oxide Particle

1 kg of the precursor A and lithium hydroxide (LiOH H₂O) were mixed in ahigh-speed mixer at a Li/M molar ratio of 1.06, and a temperature wasraised to 760° C. at an temperature increase rate of 2.5° C./min in aNoritake kiln (RHK Simulator) to be maintained at 760° C. for 10 hours.Oxygen was passed continuously at a flow rate of 40 mL/min duringraising and maintaining the temperature. After sintering, naturalcooling was performed to room temperature, pulverization andclassification were performed to obtain preliminary lithium compositeoxide particles.

(3) Post-Treatment

200 g of the preliminary lithium composite oxide particles weredry-coated by 0.5 wt %, 0.2 wt %, and 0.1 wt % of each Al₂O₃, TiO₂ andZrO₂ having a nano-scale particle size through a high-speed coater, andthen annealed in a box-type kiln at 700° C. and with an oxygen flow rateof 5 ml/min for 6 hours. The dry-coated and heat-treated lithiumcomposite oxide particles were stirred with pure water in a 1:1 weightratio for 20 minutes and filtered under reduced pressure using a Buchnerfunnel. The filtered lithium metal composite oxide particles were driedunder vacuum at 250° C. for 24 hours and classified using 325 mesh tofinally obtain a cathode active material LiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ asa nickel-based lithium metal composite oxide.

Example 2

The same procedure as that in Example 1 was performed except that theLi/M ratio was set to 1.08 in the preparation of the preliminary lithiumcomposite oxide particles.

Example 3

The same procedure as that in Example 1 was performed except that thefiring temperature was set to 775° C. in the preparation of thepreliminary lithium composite oxide particles.

Example 4

The same procedure as that in Example 3 was performed except that theLi/M ratio was set to 1.08 in the preparation of the preliminary lithiumcomposite oxide particles.

Example 5

The same procedure as that in Example 1 was performed except that thefiring temperature was set to 790° C. in the preparation of thepreliminary lithium composite oxide particles.

Example 6

The same procedure as in Example 5 was performed except that the Li/Mratio was set to 1.08 in the preliminary lithium composite oxideparticle manufacturing process.

Example 7

From the procedure of Example 3, the preparation of the preliminarylithium composite oxide particles and the post-treatment were performedas follows:

1) Preparation of Preliminary Lithium Composite Oxide Particle

25 kg of the precursor A and lithium hydroxide (LiOH.H₂O) were mixed ina high-speed mixer at a Li/M molar ratio of 1.06, and then filled in aceramic crucible (Codilite Sagger) by 6.5 kg.

The temperature was raised to 775° C. at a temperature increasing rateof 2.5° C./min in a continuous sealed atmosphere firing furnace (RHK,Roller Hearth Kiln), and a first firing was performed under thecondition that the temperature was maintained at 775° C. for 10 hours.

An oxygen concentration in the maintaining period in the kiln was 93% ormore. A discharged cake was pulverized and classified to obtainpreliminary lithium composite oxide particles.

2) Post-Treatment Process

25 kg of the preliminary lithium composite oxide particles weredry-coated by 0.5 wt %, 0.2 wt % and 0.1 wt % of each Al₂O₃, TiO₂ andZrO₂ having a nano-scale particle size through a high-speed coater, andthen annealed in a continuous kiln (RHK) at 700° C. and with an oxygenflowing condition. The dry-coated and heat-treated lithium compositeoxide particles were stirred with pure water in a 1:1 weight ratio for20 minutes and filtered using a filter press. The filtered lithium metalcomposite oxide was dried under vacuum at 250° C. for 24 hours using arotary vacuum dryer, and classified using 325 mesh to finally obtain acathode active material LiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ which was anickel-based lithium metal composite oxide.

Comparative Example 1

5 m³ of water was put into a sealed co-precipitation reactor equippedwith a stirrer and a concentrator and having a volume of 5.5 m³, andthen nitrogen gas was bubbled for at least 4 hours to remove internaldissolved oxygen w % bile maintaining an internal temperature at 63° C.12.1 kg of NaOH was added to the reactor, and 28% aqueous ammonia wasadded to the reactor to adjust a concentration of NH₃ to 24 g/L.

A pH of the obtained reaction solution was 11.6.

While initially stirring the reaction solution at 175 rpm, NiSO₄.6H₂O,CoSO₄.7H₂O and MnSO₄.H₂O were used to prepare a 2.0M metal mixed aqueoussolution with a molar ratio of Ni:Co:Mn=0.8:0.1:0.1. 2.2 M NaOH solutionas a pH control agent and 4.5 M ammonia solution as a chelating agentwere continuously added while bubbling N₂ to proceed with aco-precipitation reaction.

A residual liquid was continuously discharged to an outside of thereactor by the concentrator during the reaction, and the reactionproceeded for 77 hours while solid contents remained in the reactor.

The initial pH of 11.6 and the stirring rate of 175 rpm were graduallyreduced to 10.08 and of 135 rpm, respectively, until the reaction wascompleted to prevent a generation of new fine particles due to theincrease of the solid contents as the reaction proceeded.

The solids content in the final reactor was 37.2 wt %. A mother liquorafter the reaction completed was washed sequentially using 2.2M NaOHsolution and pure water, filtered and then dried at 120° C. for 12 hoursto obtain 3.3 tons of Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)₂ as a high-densitymetal composite hydroxide (a precursor C) which had an average particlesize (D₅₀) 13.7 μm, a tap density 2.03 g/cc, a BET 9.80 m²/g.

Processes the same as that in Example 1 for preparing the preliminarylithium composite oxide particle and the post-treatment were performedexcept that the precursor C was used.

Comparative Example 2

The same procedure as that in Comparative Example 1 was performed exceptthat the Li/M ratio was set to 1.08 in the preparation of thepreliminary lithium composite oxide particle.

Comparative Example 3

From the procedure of Comparative Example 2, the preparation of thepreliminary lithium composite oxide particles and the post-treatmentwere performed as follows:

1) Preparation of Preliminary Lithium Composite Oxide Particle

25 kg of the precursor C and lithium hydroxide (LiOH.H₂O) were mixed ina high-speed mixer at a Li/M molar ratio of 1.08, and then filled in aceramic crucible (Codilite Sagger) by 6.5 kg.

The temperature was raised to 760° C. at a temperature increasing rateof 2.5° C./min in a continuous sealed atmosphere firing furnace (RHK,Roller Hearth Kiln), and a first firing was performed under thecondition that the temperature was maintained at 760° C. for 10 hours.

An oxygen concentration in the maintaining period in the kiln was 93% ormore. A discharged cake was pulverized and classified to obtainpreliminary lithium composite oxide particles.

2) Post-Treatment Process

The preliminary lithium composite oxide particle obtained above waspost-treated by the method the same as that in Example 7 to obtain acathode active material LiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ which was anickel-based lithium metal composite oxide.

Comparative Example 4

5 m³ of water was put into a sealed co-precipitation reactor equippedwith a stirrer and a concentrator and having a volume of 5.5 m³, andthen nitrogen gas was bubbled for at least 4 hours to remove internaldissolved oxygen while maintaining an internal temperature at 63° C.13.5 kg of NaOH was added to the reactor, and 28% aqueous ammonia wasadded to the reactor to adjust a concentration of NH₃ to 24 g/L. A pH ofthe obtained reaction solution was 11.75.

While initially stirring the reaction solution at 175 rpm. NiSO₄.6H₂O,CoSO₄.7H₂O and MnSO₄.H₂O were used to prepare a 2.0M metal mixed aqueoussolution with a molar ratio of Ni:Co:Mn=0.8:0.1:0.1. 2.2 M NaOH solutionas a pH control agent and 4.5 M ammonia solution as a chelating agentwere continuously added while bubbling N₂ to proceed with aco-precipitation reaction.

A residual liquid was continuously discharged to an outside of thereactor by the concentrator during the reaction, and the reactionproceeded for 90 hours while solid contents remained in the reactor.

The initial pH of 11.75 and the stirring rate of 175 rpm were graduallyreduced to 10.21 and of 130 rpm, respectively, until the reaction wascompleted to prevent a generation of new fine particles due to theincrease of the solid contents as the reaction proceeded.

The solids content in the final reactor was 43.0 wt %. A mother liquorafter the reaction completed was washed sequentially using 2.2M NaOHsolution and pure water, filtered and then dried at 120° C. for 12 hoursto obtain 4 tons of Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)₂ as a high-densitymetal composite hydroxide (a precursor B) which had an average particlesize (D₅₀) 13.3 μm, a tap density 2.06 g/cc, a BET 6.81 m²/g.

Processes the same as that in Example 1 for preparing the preliminarylithium composite oxide particle and the post-treatment were performedexcept that the precursor B was used.

Comparative Example 5

The same procedure as that in Comparative Example 3 was performed exceptthat the temperature was set to 775° C. in preparation of thepreliminary lithium composite oxide particle while using the precursorB.

Comparative Example 6

The same procedure as that in Comparative Example 3 was performed exceptthat the temperature was set to 790° C. in preparation of thepreliminary lithium composite oxide particle while using the precursorB.

Experimental Example 1

(1) Analysis on Surface Structure

Surface images of the composite hydroxide particles according toExamples and Comparative Examples were obtained using a scanningelectron microscope (SEM).

FIG. 2 is an SEM image of a precursor particle (a composite hydroxideparticle) for a cathode active material according to exemplaryembodiments.

Referring to FIG. 2, it was confirmed that the composite hydroxideparticles according to Example 1 had a secondary particle structure inwhich primary particles were aggregated. Further, a surface shape of theprimary particle was approximately triangular, and a length ratio (theaspect ratio) of a short side to a long side of the triangle was 0.5 ormore.

FIG. 3 is an SEM image of composite hydroxide particles used inComparative Examples 1 to 3. FIG. 4 is an SEM image of compositehydroxide particles used in Comparative Examples 4 to 6.

Referring to FIGS. 3 and 4, it was confirmed that the primary precursorparticles of Comparative Examples were needle-shaped. The aspect ratioof the needle-shaped particles was calculated as a ratio of a length ofa minor axis (the shortest axis within the particle) to a length of amajor axis (the longest axis within the particle). It was confirmed thatthe composite hydroxide particles of Comparative Examples had aremarkably large specific surface area.

FIG. 5 is an SEM image of a preliminary lithium composite oxide particleformed from composite hydroxide particles of Example 1. FIGS. 6 and 7are SEM images of primary fired particles formed from compositehydroxide particles of Comparative Examples 1 and 4, respectively.

Referring to FIGS. 5 to 7, surface shape and specific surface area ofthe cathode active material were changed depending on the surface shapesand specific surface areas of the composite hydroxide particles evenwhen the first firing was performed under the same conditions (760° C.,Li/M=1.06). The size and specific surface area of the primary particleof the composite hydroxide particle were substantially proportional tothe size and specific surface area of the primary particle of thepreliminary lithium composite oxide particle.

FIGS. 8 and 9 are SEM images of cathode active materials for a secondarybatteries of Example 7 and Comparative Example 3, respectively.

Referring to FIGS. 8 and 9, even though dimensions of the first firingand post-treatment processes became greater, the size and specificsurface area of the primary particle of the composite hydroxide particlewere substantially proportional to the size and specific surface area ofthe preliminary lithium composite oxide particle.

(2) Analysis on BET (Specific Surface Area)

BETs of the composite hydroxide particles and preliminary lithiumcomposite oxide particles according to Examples and Comparative Exampleswere measured by a gas adsorption/desorption method using a BETmeasuring instrument (ASAP2420) of Micrometrics. The results are shownin Table 1 below.

The precursor A used in Examples 1 to 7 had a specific surface area of1.0 m²/g or less, which was significantly smaller than those ofComparative Examples, and the specific surface area of the preliminarylithium composite oxide particle was also maintained as 0.12 m²/g orless.

TABLE 1 Preliminary lithium Precursor composite oxide particle Shape ofprimary particle Firing BET (aspect Tem- Li/M BET Grain Type (m²/g)ratio) perature ratio (m²/g) Shape Example 1 A 0.89 triangle 760° C.1.06 0.111 amorphous Example 2 (0.87) 760° C. 1.08 0.101 Example 3 775°C. 1.06 0.095 Example 4 775° C. 1.08 0.093 Example 5 790° C. 1.06 0.094Example 6 790° C. 1.08 0.091 Example 7 775° C. 1.06 0.095 Comparative C9.80 needle- 760° C. 1.06 0.141 hexahedron Example 1 shape Comparative(0.1 or 760° C. 1.08 0.133 Example 2 less) Comparative 760° C. 1.080.132 Example 3 Comparative B 6.81 Needle- 760° C. 1.06 0.136 hexahedronExample 4 shape Comparative (0.05 or 775° C. 1.06 0.129 Example 5 less)Comparative 790° C. 1.06 0.122 Example 6

Experimental Example 2: Coin Cell Fabrication and Evaluation

(1) Fabrication of Coin Half Cell

Lithium metal oxide particles of Examples and Comparative Examples, acarbon black as a conductive agent, and a polyvinylidene fluoride (PVdF)as a binder were mixed in a weight ratio of 92:5:3 to prepare a slurry.The slurry was uniformly coated on an aluminum foil having a thicknessof 15 μm, and vacuum dried at 130° C. to prepare a cathode. An electrodeassembly was formed using the cathode, a lithium foil as a counterelectrode and a porous polyethylene layer (thickness: 21 μm) as aseparator.

A coin half cell was fabricated by a conventionally known manufacturingprocess using the electrode assembly and a liquid electrolyte includingLiPF (dissolved with a concentration of 1.0M in a solvent in whichethylene carbonate and ethylmethyl carbonate were mixed in a volumeratio of 3:7, and evaluated at a voltage from 3.0V to 4.3V.

(2) Measurement of Initial Charge/Discharge Capacity

Initial charging and discharging capacities were measured by performingcharging (CC/CV 0.1 C 4.3V 0.05 C CUT-OFF) and discharging (CC 0.1 C3.0V CUT-OFF) once for the prepared battery cells (CC: constant current.CV: constant voltage).

(3) Measurement of Initial Efficiency

An initial efficiency was calculated as a percentage value obtained bydividing the initial discharge capacity by the initial charge capacity.

(4) Evaluation of Life-Span at Room Temperature

Charging (CC/CV 0.5 C 4.3V 0.05 C CUT-OFF) and discharging (CC 1.0 C3.0V CUT-OFF) for the battery cells according to Examples andComparative Examples were repeated 300 times at 25° C. A capacityretention ratio was evaluated as a percentage value obtained by dividingthe discharge capacity at the 300th cycle by the discharge capacity atthe 1st cycle.

(5) Evaluation of Life-Span at Room Temperature

Charging (CC/CV 0.33 C 4.3V 0.05 C CUT-OFF) and discharging (CC 0.33 C3.0V CUT-OFF) for the battery cells according to Examples andComparative Examples were repeated 100 times at 45° C. A capacityretention ratio was evaluated as a percentage value obtained by dividingthe discharge capacity at the 100th cycle by the discharge capacity atthe 1st cycle.

The results are shown in Table 2 below.

TABLE 2 Capacity Capacity Retention Retention at room at high DischargeInitial temperature temperature Capacity Efficiency (%) (%) (mAh/g) (%)@300cycle @100cycle Example 1 195 88.2 89 88 Example 2 199 89.6 88 89Example 3 198 89,1 90 92 Example 4 197 89.9 89 91 Example 5 192 87.9 8890 Example 6 195 88.3 87 90 Example 7 201 89.6 90 91 Comparative 19688.3 91 72 Example 1 Comparative 199 89.8 90 73 Example 2 Comparative203 90.7 91 70 Example 3 Comparative 200 89.7 91 75 Example 4Comparative 196 88.9 87 73 Example 5 Comparative 194 88.8 85 75 Example6

Referring to Table 2, the secondary batteries including the cathodeactive material formed from the precursors of Examples providedremarkably improved high-temperature life-span properties whilemaintaining substantially the same level of the capacity androom-temperature life-span properties as those of Comparative Examples.

Experimental Example 3: Fabrication and Evaluation of Lithium SecondaryBattery (Full Cell)

(1) Fabrication of Lithium Secondary Battery (Full Cell)

The cathode electrode active materials prepared in Example 7 andComparative Example 3, Denka Black as a conductive agent and a PVDFbinder were mixed in a mass ratio of 92:5:3 to prepare a cathodemixture. The cathode mixture was coated on an aluminum substrate, driedand pressed to prepare a cathode.

An anode mixture containing 93 wt % of natural graphite (d₀₀₂: 3.358 Å)as an anode active material, 5 wt % of KS6 as a flake-type conductiveagent, 1 wt % of SBR binder and 1 wt % of CMC thickener was coated on acopper substrate, dried and pressed to prepare an anode.

The cathode and the anode obtained as described above were notched witha proper size and stacked, and a separator (polyethylene, thickness: 25μm) was interposed between the cathode and the anode to form anelectrode cell. Each tab portion of the cathode and the anode waswelded.

The welded cathode/separator/anode assembly was inserted in a pouch, andthree sides of the pouch except for one side were sealed. The tabportions were also included in sealed portions. An electrolyte wasinjected through the one side except for the sealed portions, and thenthe one side was also sealed. Subsequently, the above structure wasimpregnated for more than 12 hours.

The electrolyte was prepared by dissolving 1M LiPF₆ in a mixed solventof EC/EMC/DEC (25/45/30; volume ratio), and then 1 wt % of vinylenecarbonate, 0.5 wt % of 1,3-propensultone (PRS), and 0.5 wt % of lithiumbis(oxalato) borate (LiBOB) were added.

Thereafter, pre-charging was performed for 36 minutes with a current(2.5 A) corresponding to 0.25 C. After 1 hour, degasing and aging formore than 24 hours were performed and then a charging and dischargingfor a formation was performed (charge condition CC-CV 0.2 C 4.2V 0.05 CCUT-OFF, discharge condition CC 0.2 C 2.5V CUT-OFF). Subsequently, astandard charging and discharging was performed (charge condition CC-CVLOC 4.2V 0.05 C CUT-OFF, discharge condition CC 1.0 C 2.5V CUT-OFF).

(4) Evaluation of Life-Span Property

Charging (CC-CV 1.0 C 4.15V 0.05 C CUT-OFF) and discharging (CC 1.0 C3.1V CUT-OFF) for each secondary battery were repeated 2,000 times. Acapacity retention ratio was evaluated as a percentage value obtained bydividing the discharge capacities at the 800th and 2.000th cycles by thedischarge capacity at the 1st cycle.

(3) Evaluation of High Temperature Storage Property

Each of the prepared lithium secondary batteries was charged under thecondition of CC-CV 1.0 C 4.2V 0.05 C CUT-OFF and stored in an oven at60° C. for 8 weeks. Thereafter, the battery was discharged under thecondition of CC 0.5 C 2.5V CUT-OFF, and then charged under the conditionof CC-CV 0.5 C 4.2V 0.05 C CUT-OFF. Subsequently, a discharging capacityunder the condition of CC 0.5 C 2.5V CUT-OFF was measured. A capacityretention ratio was calculated by comparing the discharge capacity witha discharge capacity during a standard charging and discharging. Theresults are shown in Table 3 below.

TABLE 3 Capacity Retention (%) Capacity Retention (%) after high at roomtemperature temperature storage 800th cycle 2,000th cycle 8 weeks 12weeks Example 7 96% 85% 90% 76% Comparative 96% 86% 80% 58% Example 3

Referring to Table 2, the secondary batteries including the cathodeactive material formed from the precursors of Examples providedremarkably improved high-temperature life-span properties whilemaintaining substantially the same level of the capacity androom-temperature life-span properties as those of Comparative Examples.

What is claimed is:
 1. A cathode active material precursor comprising acomposite hydroxide particle in which primary precursor particles areaggregated, wherein the primary precursor particles include a particlehaving a triangular shape in which a minimum interior angle is 30° ormore and a ratio of a length of a short side relative to a length of along side is 0.5 or more.
 2. The cathode active material precursor ofclaim 1, wherein the composite hydroxide particle contains an excess ofnickel among metals included therein and has a specific surface area of1.5 m²/g or less.
 3. The cathode active material precursor of claim 2,wherein the composite hydroxide particle has a specific surface area of1 m²/g or less.
 4. The cathode active material precursor of claim 2,wherein a molar ratio of nickel in the metals included in the compositehydroxide particle is 0.8 or more.
 5. The cathode active materialprecursor of claim 2, wherein the composite hydroxide particle furtherincludes cobalt.
 6. The cathode active material precursor of claim 5,wherein the composite hydroxide particle further includes manganese. 7.The cathode active material precursor of claim 1, wherein the compositehydroxide particle is represented by Chemical Formula 1:Ni_(α)Co_(β)M_(γ)(OH)_(z)  [Chemical Formula 1] wherein in ChemicalFormula 1, M includes at least one selected from the group consisting ofMg, Sr, Ba, B, Al, Si, Mn, Ti, Zr and W, 0.8≤α≤0.95, 0≤γ/(α+β)≤0.13,0≤γ≤0.11 and 1.9≤z≤2.1.
 8. The cathode active material precursor ofclaim 1, wherein the ratio of the length of the short side relative tothe length of the long side is 0.8 or more.
 9. A cathode active materialfor a secondary battery, comprising a lithium composite oxide particleformed from the cathode active material precursor of claim
 1. 10. Thecathode active material for a secondary battery of claim 9, wherein thelithium composite oxide particle has an amorphous shape.
 11. A lithiumsecondary battery, comprising: a cathode comprising the cathode activematerial of claim 9; and an anode facing the cathode.
 12. A method ofmanufacturing a cathode active material precursor, comprising: preparinga reaction solution containing a metal source; and forming aco-precipitate through a co-precipitation reaction in the reactionsolution, wherein a solid content in the reaction solution is 50 wt % ormore after the co-precipitation reaction, wherein a composite hydroxideparticle is formed in which primary precursor particles are aggregatedby the co-precipitation reaction, and the primary precursor particlesinclude a particle having a triangular shape in which a minimum interiorangle is 300 or more and a ratio of a length of a short side relative toa length of a long side is 0.5 or more.
 13. The method of claim 12,wherein the co-precipitation reaction is performed under a condition inwhich a pH value is changed from 11.8 or more to 10.8 or less.
 14. Themethod of claim 12, wherein the co-precipitation reaction is performedfor 120 hours or more.
 15. A method of manufacturing a cathode activematerial for a secondary battery, comprising: preparing the cathodeactive material precursor of claim 1: forming a preliminary lithiumcomposite oxide particle by reacting the cathode active materialprecursor with a lithium source; and post-treating the preliminarylithium composite oxide particle.
 16. The method of claim 15, whereinthe preliminary lithium composite oxide particle has a specific surfacearea of 0.12 m²/g or less.
 17. The method of claim 15, wherein thepost-treating comprises at least one of coating, heat-treating, washingand drying.
 18. The method of claim 15, wherein the forming thepreliminary lithium composite oxide particle comprises firing afterreacting the cathode active material precursor with the lithium source.